The next generation of optical information processing, at the telecommunication wavelength of 1.3-1.6 μm, can be based on an integrated platform. Such a platform can also be important for on-chip chemical/biological sensing, particularly in the mid-infrared spectral range of 2-30 μm. However, certain challenges on the device level can prevent reliable integration on a large scale. These challenges include miniaturizing the device footprint, increasing the operating bandwidth and robustness, and reducing power consumption.
Many integrated photonic devices are based on coupled waveguides, which are typically hundreds of microns to millimeters in length because of the weak coupling between waveguides via evanescent waves. Micro-ring resonators and photonic-crystal cavities can have large quality factors (Q-factors) and enable a great variety of small-footprint photonic devices. A drawback of certain approaches, however, is that the device performance is highly susceptible to interference, such as temperature changes and fabrication errors, and such devices typically have a narrow spectral operating range. Accordingly, there exists a need for a technique to provide lightweight, miniature, and broadband integrated photonics devices.